“The soul that rightly prays, it must be in and with the help and strength of the Spirit; because it is impossible that a man should express himself in prayer without it. By this I mean that it is impossible that the heart, in a sincere and affectionate way, should pour out itself before God, with those groans and sighs that come from a truly praying heart, without the assistance of the Spirit. It is not the mouth that is the main thing to be looked at in prayer, but whether the heart is so full of affection and earnest in prayer with God that it is impossible to express their sense and desire; for then a man desires indeed when his desires are so strong, many, and mighty, that all the words, tears and groans that come from the heart cannot utter them: ‘The Spirit helpeth our infirmities, and maketh intercession for us with’ sighs and ‘groanings which cannot be uttered’ (Rom. 8:26).
That is but poor prayer which is only one of words. A man that truly prays one prayer cannot express with his mouth or pen the unutterable desires, sense, affection, and longing that went to God in his prayer. The best prayers have often more groans than words: and those words that they have are but a lean and shallow representation of the heart, life and spirit of prayer.”
– John Bunyan, Prayer, p.32-33